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747-400 MAINTENANCE MANUAL
(c) The TANK TO ENGINE ALERT discrete not set when: 1) the airplane is in refuel mode (the refuel control panel is open).
2) the airplane transitions from GROUND to AIR mode (for eight minutes). If the TANK TO ENGINE ALERT discrete was set before the transition, the discrete will continue to be active after the AIR mode inhibit.
(16)
During the refuel operation for the next flight, if all of the main tanks are refueled with less than 30,000 pounds (13,600 kilograms) and the inboard main tanks contain more fuel than the outboard main tanks, it is possible to get two different system configurations with the same fuel quantity in each tank:
(a)
If the FUEL TANK/ENGINE ALERT discrete was set on the previous flight and the fuel quantity for each of the inboard main tanks is less than 32,000 pounds (14,500 kilograms), then the No. 1 and the No. 4 crossfeed valves must be closed.
(b)
If the FUEL TANK/ENGINE ALERT discrete was not set, and the fuel quantity in each of the inboard main tanks is more than the fuel quantity in each of the applicable outboard main tanks, then the No. 1 and the No. 4 crossfeed valves must be opened.
(c)
During flight, the flight crew action for each of the crossfeed valve configurations is as follows: 1) If the X FEED CONFIG message shows, crossfeed valves No. 1
and No. 4 are opened until one of the inboard main tanks becomes less than or equal to the applicable outboard main tank. At this time the FUEL TANK/ENG message will show until the No. 1 and the No. 4 crossfeed valves are closed.
2) If the FUEL TANK/ENG message shows, the No. 1 and the No. 4 crossfeed valves must be closed.
(17)
To terminate engine fuel feed system operation, the boost pump and override/jettison pumps are turned off and the crossfeed valves are closed.
B.
Control (Fig. 7)
(1)
Provide 28-volt dc and 115-volt ac power to the fuel feed system.
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747-400
MAINTENANCE MANUAL
DISTRIBUTION FUEL MANAGEMENT PANEL CONTROL MODULE (P5)
FUEL BOOST PUMP (TYPICAL)
Engine Fuel Feed System Simplified Schematic
Figure 6 (Sheet 1)
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747-400
MAINTENANCE MANUAL
ENGINE FUEL SHUTOFF VALVE (TYPICAL)
Engine Fuel Feed System Simplified Schematic
Figure 6 (Sheet 2)
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747-400
MAINTENANCE MANUAL
28V DC BAT BUS (P6)
FUEL CROSSFEED VALVE - OUTBOARD (TYPICAL)
